The invention relates to a sensor arrangement and to a method for determining an angle of rotation.
Modern electrical power-assisted steering systems for motor vehicles control the steering force assistance on the basis of a torque impressed by the driver. This torque is converted into a differential angle signal by a torsion bar of defined rigidity between an input shaft and an output shaft. In this case, a measurement range for the torque of +/−8 Nm corresponds to a differential angle of +/−4°, for example. This differential angle is measured by a so-called torque sensor which is arranged in the region of the input and output shafts. For further processing, the torque sensor provides a signal proportional to the differential angle and the torque.
The document DE 199 58 504 A1 proposes a sensor arrangement for detecting the angle of rotation and/or the torque of rotating mechanical parts. In this case, a torsion shaft is arranged, as an outer shaft, on a rotating part, a torque acting on a first end of the part and the torque being taken off at a second end. An inner shaft is arranged concentrically with respect to the outer shaft and its first end is fastened to the outer shaft in the region in which the torque is input. Magnets are arranged at the end of the outer shaft and inner shaft, said magnets having magnetic fields which are radially oriented with respect to the axes of the shafts and each being assigned a stationary sensor.
Under the action of the torque, the rotation of the magnetic fields relative to one another can be measured, the angle of rotation being proportional to the torque.
A sensor arrangement and a method for producing a sensor arrangement are known from the document DE 10 2007 028 483 A1. In this case, the sensor arrangement has at least one magnetic flux collection element which can be used to supply the magnetic flux of a magnetic circuit to a sensor element. The magnetic flux collection element consists of at least two parts which at least partially overlap in an overlapping region, the two parts being at least partially surrounded by an encapsulation and being held in a particular position with respect to one another.